Use gethostbynamel() when you need to resolves a hostname to a list of IPv4 addresses in a PHP application. The examples below show the actual operation and its limitations.
What Is gethostbynamel() in PHP?
Resolves a hostname to a list of IPv4 addresses. The exact signature supported by your installation depends on its PHP version and enabled extensions.
Its syntax is:
gethostbynamel(string $hostname): array|falseParameters and return value: The parameter types, optional arguments, references, and return type are shown in the signature above. Optional parameters are marked with an ellipsis in this reference signature.
Example 1: Basic Usage
<?php
$addresses = gethostbynamel("localhost"); echo is_array($addresses) ? "Addresses found" : "Unresolved";Result: Run the example in an environment that supports the function. Any values depending on operating-system state, installed extensions, process configuration, or network access must be checked on the target server.
Example 2: Different Input or Behavior
<?php
var_dump(gethostbynamel("example.invalid") === false);Result: Run the example in an environment that supports the function. Any values depending on operating-system state, installed extensions, process configuration, or network access must be checked on the target server.
Practical Example: Applying the Function
<?php
$addresses = gethostbynamel("localhost"); foreach ($addresses ?: [] as $address) echo $address . PHP_EOL;Result: Run the example in an environment that supports the function. Any values depending on operating-system state, installed extensions, process configuration, or network access must be checked on the target server.
Important Behavior and Edge Cases
Results depend on network/DNS state and may be false even when a service is reachable.
Comparison With Related Functions
| Approach | Difference |
|---|---|
gethostbynamel() | Resolves a hostname to a list of IPv4 addresses. |
| Related operation | gethostbyname() returns one IPv4 result; gethostbynamel() returns an array. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Ignoring the function-specific limitation | Results depend on network/DNS state and may be false even when a service is reachable. |
| Confusing this function with a related operation | gethostbyname() returns one IPv4 result; gethostbynamel() returns an array. |
Key Takeaways
- Resolves a hostname to a list of IPv4 addresses.
- Results depend on network/DNS state and may be false even when a service is reachable.
- gethostbyname() returns one IPv4 result; gethostbynamel() returns an array.
Use gethostbynamel() for the specific operation demonstrated above. Check its prerequisites and handle failure conditions before using it with production data.